I realize I am late at this, I have been busy and did not check the forum for a while and when I get back I find this, what I see has simply become the "CCE Mod".

I am so impressed with your work guys, you have taken a centennial technology and found something new in it, I am indeed impressed. From the descriptions it sounds very much like another unresolved mystery of the tube world, the odd "bloom" that tube amps experience after they have been on sometime. It really looks like we are still far away from totally understanding tubes and I certainly cannot see the end of this technology anywhere or anytime soon.

the D amps seemed to challenge the tube world, but clearly the force is still strong in tubeland

There is presently a discussion going on at the DIY audio forums about the CCE (or Hazen) mod. I've written a part II to the paper talking more about how it works to perpetuate more discussion about it.

Thanks for the info Karl. Another question please. Pin 6 is empty on both sockets now, that's easy. Each pin 3 has a single wire coming off it. One is red, the other is white and they tie together at a large gold colored(resistor?) Those wires should remain undisturbed right? And no problems using a mylar capacitor, correct?

Ok, never mind, I could not wait. Soldered the caps in, put it all back together and started it up. I had a fire extinguisher in hand and safety glasses on. So far very good. I hooked up an old dvd and my bookshelf speakers for a test. Spent a few minutes with Johnny A spinning - the amp sounds lusher, fuller. Changing the bias setting seems to have more of a difference now too. My little Boston HD7s are only five feet away from me and they have completely disappeared. I call that a success. I am quite pleased with the low quality gear I am testing it with. With the Zbox, Dec 685, and my nibblelin NFx I expect it will even get better.

I guess it´s in my nature to always ask questions? so I hope you will bear with me.

why is the value of the cap 0.1uf? and have you tried other values and with what results? ohh and while we are at it, why is the quality of the cap not important. I mean is that ever true?I guess at this stage only steve and the guru Hazen himself may have an answer?

I'm just wondering if you have it on a switch. Even with a switch it can be hard to catch because the effect takes several seconds to build up before it is noticed. You almost have to be listening with it on, and then turn it off to hear an immediate change.

why is the value of the cap 0.1uf? and have you tried other values and with what results? ohh and while we are at it, why is the quality of the cap not important. I mean is that ever true?I guess at this stage only steve and the guru Hazen himself may have an answer?

The 0.1uf value was used to place the effect inside the audio band where it would have an effect on the upper bass on out to the treble region. Changing the value changes the time constant which will effect where in the frequency band it acts and also how images present themselves in the sound stage. Using a 0.01 for example would push the effect up so high in the frequency band that if anything were noticed it would only be in the upper treble.

Bump/// Is this mod a regular feature of the current Zen Triode amps that ship with the SV83 output tubes?... It would seem like the prudent thing to do... Gotta admit, I'm pretty much out-of-the-loop here... Not all that technically proficient on tube technology... (m.)

If a rabbit defined intelligence the way man does, then the most intelligent animal would be a rabbit, followed by the animal most willing to obey the commands of a rabbit. -Robert Brault, writer (b. 1938)

Sounds like my coming out of suspended animation after 10 years is already paying off as I never heard of this cap mod! I'm sure I have some .1uf, 500V or 600V caps lying about -- probably russian teflons I bought years ago and I suspect they shouldn't hurt the sound vs poly.

Just checked the pin-out on the EL34 and looks like the place for the cap is between pins 1 and 8 to cap-connect the cathode and suppressor grid.

I read both white papers from 2009 -- interesting stuff. Can't say I understand what's going on yet. I'll plug in the mod today on my first gen modded Torii and see what it does. Easily reversible if not liked, but somehow I expect good things.

Been so long since any mods done on my Torii the dust is getting thick, lol! :-)